Modern medical devices, including medical pumps, are increasingly being controlled by microprocessor based systems to deliver fluids, solutions, medications, and drugs to patients. A typical control for a medical pump includes a user interface enabling a medical practitioner to enter the dosage of fluid to be delivered, the rate of fluid delivery, the duration, and the volume of a fluid to be infused into a patient. Typically, drug delivery is programmed to occur as a continuous infusion or as a single bolus dose.
It is common for a plurality of fluids to be infused to a patient by using a multi-channel infusion pump or using a plurality of single channel infusion pumps where a different fluid is administered from each channel. Another method of infusing multiple fluids to a patient is the piggyback method.
The piggyback method allows an infusion pump to deliver fluid from a secondary container at a rate and volume similar to or different from that of a primary container. Typically, the fluid paths from the primary container and secondary container meet at a Y-joint intersection located above or upstream of the pump. Downstream of the Y-site, the IV tube set is then inserted into a single channel of an infusion pump. The secondary container must be suspended at a higher position on the IV pole so that the resulting higher head height creates a higher pressure in the IV tube. The microprocessor is programmed to stop an infusion and allow the user to switch the source of the infusion. With its superior pressure, the secondary container's flow interrupts the flow from the first container and allows a different fluid to be infused through the single channel on an interrupt basis. This method requires manual intervention, may require additional mechanical components such as a clamp or valve, and requires that multiple medications be delivered through a single channel. At the end of the secondary infusion, the secondary bag must generally be removed and infusion from the primary bag must be manually restarted.
Another method for infusing multiple fluids is disclosed in U.S. Pat. No. 4,696,671 and U.S. Pat. No. 5,464,392. In the infusion pump disclosed therein, a complex pump cassette with plural inlets and a single outlet is used to sequence and mix the flow of fluids from multiple sources through a single tube set. A plurality of valves must be included in the pump and operated by its processor according to a real time clock to control the flow of fluid through the cassette. This was a significant improvement over the manual manipulation of clamps, Y-sites, and valves that had been required, but moving the valves to the pump and automating them significantly added to the cost and complexity of the pump. Furthermore, the cassette could not be removed from the pump so long as any one of the plurality of inlet ports were being utilized to pump fluid from any of the sources. The single outlet of the cassette also fails to provide the flexibility to deliver the fluids through separate and distinct outlet or tubes to the patient, which may be desirable.
Another method for infusing multiple fluids is the use of a multi-channel infusion pump which delivers a separate fluid through each channel. In such infusion pumps, an individual therapy that is being delivered through a particular channel would have to be programmed and completely dispensed through that channel. After that individual therapy was dispensed, a new therapy on another channel could be programmed and dispensed. In this manner, multiple channels could not be programmed at a single time. Instead, each channel had to be programmed and started individually. As a result, the method was manual and required excessive user intervention. The present invention is provided to solve these and other problems.